Fixing 500 error when entering a bad itemid when creating an auction

GameAuthApi.Tests/ServiceValidationTests.cs

@@ -0,0 +1,32 @@
+using GameAuthApi.Services;
+using Microsoft.Extensions.Configuration;
+
+public class ServiceValidationTests
+{
+    private static IConfiguration cfg = new ConfigurationBuilder()
+        .AddInMemoryCollection(new Dictionary<string,string>
+        {
+            {"MongoDB:ConnectionString","mongodb://localhost"},
+            {"MongoDB:DatabaseName","test"}
+        }).Build();
+
+    [Fact]
+    public async Task ItemService_InvalidId_ReturnsNull()
+    {
+        var svc = new ItemService(cfg);
+
+        var result = await svc.GetByIdAsync("bad");
+
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public async Task AuctionService_InvalidId_ReturnsNull()
+    {
+        var svc = new AuctionService(cfg);
+
+        var result = await svc.GetByIdAsync("bad");
+
+        Assert.Null(result);
+    }
+}

Services/AuctionService.cs

@@ -20,8 +20,13 @@ public class AuctionService
     public virtual async Task CreateAsync(Auction auction) =>
         await _auctions.InsertOneAsync(auction);
 
-    public virtual async Task<Auction> GetByIdAsync(string id) =>
+    public virtual async Task<Auction> GetByIdAsync(string id)
-        await _auctions.Find(a => a.Id == id).FirstOrDefaultAsync();
+    {
+        if (!MongoDB.Bson.ObjectId.TryParse(id, out _))
+            return null;
+
+        return await _auctions.Find(a => a.Id == id).FirstOrDefaultAsync();
+    }
 
     public virtual async Task UpdateAsync(Auction auction) =>
         await _auctions.ReplaceOneAsync(a => a.Id == auction.Id, auction);

Services/ItemService.cs

@@ -29,6 +29,9 @@ public class ItemService
 
     public virtual async Task<Item> GetByIdAsync(string id)
     {
+        if (!MongoDB.Bson.ObjectId.TryParse(id, out _))
+            return null;
+
         return await _items.Find(i => i.Id == id).FirstOrDefaultAsync();
     }